From 5b1658232e7a379cc7c354de625fbf497147bc6f Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Tue, 5 Jul 2011 16:02:34 +1000
Subject: exp/template: statically check that functions names have been
 defined.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4675046
---
 src/pkg/exp/template/parse.go      | 28 ++++++++++++++++++++++++----
 src/pkg/exp/template/parse_test.go | 21 +++++++++------------
 src/pkg/exp/template/set.go        |  2 +-
 3 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/src/pkg/exp/template/parse.go b/src/pkg/exp/template/parse.go
index aaed411d49..8514399b82 100644
--- a/src/pkg/exp/template/parse.go
+++ b/src/pkg/exp/template/parse.go
@@ -20,7 +20,8 @@ type Template struct {
 	name  string
 	root  *listNode
 	funcs map[string]reflect.Value
-	// Parsing.
+	// Parsing only; cleared after parse.
+	set      *Set
 	lex      *lexer
 	tokens   <-chan item
 	token    item // token lookahead for parser
@@ -507,14 +508,15 @@ func (t *Template) recover(errp *os.Error) {
 }
 
 // startParse starts the template parsing from the lexer.
-func (t *Template) startParse(lex *lexer, tokens <-chan item) {
+func (t *Template) startParse(set *Set, lex *lexer, tokens <-chan item) {
 	t.root = nil
+	t.set = set
 	t.lex, t.tokens = lex, tokens
 }
 
 // stopParse terminates parsing.
 func (t *Template) stopParse() {
-	t.lex, t.tokens = nil, nil
+	t.set, t.lex, t.tokens = nil, nil, nil
 }
 
 // atEOF returns true if, possibly after spaces, we're at EOF.
@@ -541,7 +543,19 @@ func (t *Template) atEOF() bool {
 // Parse parses the template definition string to construct an internal representation
 // of the template for execution.
 func (t *Template) Parse(s string) (err os.Error) {
-	t.startParse(lex(t.name, s))
+	lexer, tokens := lex(t.name, s)
+	t.startParse(nil, lexer, tokens)
+	defer t.recover(&err)
+	t.parse(true)
+	t.stopParse()
+	return
+}
+
+// ParseInSet parses the template definition string to construct an internal representation
+// of the template for execution. Function bindings are checked against those in the set.
+func (t *Template) ParseInSet(s string, set *Set) (err os.Error) {
+	lexer, tokens := lex(t.name, s)
+	t.startParse(set, lexer, tokens)
 	defer t.recover(&err)
 	t.parse(true)
 	t.stopParse()
@@ -701,6 +715,9 @@ func (t *Template) templateControl() node {
 	var name node
 	switch token := t.next(); token.typ {
 	case itemIdentifier:
+		if _, ok := findFunction(token.val, t, t.set); !ok {
+			t.errorf("function %q not defined", token.val)
+		}
 		name = newIdentifier(token.val)
 	case itemDot:
 		name = newDot()
@@ -735,6 +752,9 @@ Loop:
 		case itemError:
 			t.errorf("%s", token.val)
 		case itemIdentifier:
+			if _, ok := findFunction(token.val, t, t.set); !ok {
+				t.errorf("function %q not defined", token.val)
+			}
 			cmd.append(newIdentifier(token.val))
 		case itemDot:
 			cmd.append(newDot())
diff --git a/src/pkg/exp/template/parse_test.go b/src/pkg/exp/template/parse_test.go
index 5c780cd292..70c9f5a64c 100644
--- a/src/pkg/exp/template/parse_test.go
+++ b/src/pkg/exp/template/parse_test.go
@@ -143,16 +143,12 @@ var parseTests = []parseTest{
 		`[(action: [])]`},
 	{"field", "{{.X}}", noError,
 		`[(action: [(command: [F=[X]])])]`},
-	{"simple command", "{{hello}}", noError,
-		`[(action: [(command: [I=hello])])]`},
-	{"multi-word command", "{{hello world}}", noError,
-		`[(action: [(command: [I=hello I=world])])]`},
-	{"multi-word command with number", "{{hello 80}}", noError,
-		`[(action: [(command: [I=hello N=80])])]`},
-	{"multi-word command with string", "{{hello `quoted text`}}", noError,
-		"[(action: [(command: [I=hello S=`quoted text`])])]"},
-	{"pipeline", "{{hello|world}}", noError,
-		`[(action: [(command: [I=hello]) (command: [I=world])])]`},
+	{"simple command", "{{printf}}", noError,
+		`[(action: [(command: [I=printf])])]`},
+	{"multi-word command", "{{printf `%d` 23}}", noError,
+		"[(action: [(command: [I=printf S=`%d` N=23])])]"},
+	{"pipeline", "{{.X|.Y}}", noError,
+		`[(action: [(command: [F=[X]]) (command: [F=[Y]])])]`},
 	{"simple if", "{{if .X}}hello{{end}}", noError,
 		`[({{if [(command: [F=[X]])]}} [(text: "hello")])]`},
 	{"if with else", "{{if .X}}true{{else}}false{{end}}", noError,
@@ -171,8 +167,8 @@ var parseTests = []parseTest{
 		`[({{range [(command: [F=[SI]])]}} [(action: [(command: [{{<.>}}])])])]`},
 	{"constants", "{{range .SI 1 -3.2i true false }}{{end}}", noError,
 		`[({{range [(command: [F=[SI] N=1 N=-3.2i B=true B=false])]}} [])]`},
-	{"template", "{{template foo .X}}", noError,
-		"[{{template I=foo [(command: [F=[X]])]}}]"},
+	{"template", "{{template `x` .Y}}", noError,
+		"[{{template S=`x` [(command: [F=[Y]])]}}]"},
 	{"with", "{{with .X}}hello{{end}}", noError,
 		`[({{with [(command: [F=[X]])]}} [(text: "hello")])]`},
 	{"with with else", "{{with .X}}hello{{else}}goodbye{{end}}", noError,
@@ -181,6 +177,7 @@ var parseTests = []parseTest{
 	{"unclosed action", "hello{{range", hasError, ""},
 	{"missing end", "hello{{range .x}}", hasError, ""},
 	{"missing end after else", "hello{{range .x}}{{else}}", hasError, ""},
+	{"undefined function", "hello{{undefined}}", hasError, ""},
 }
 
 func TestParse(t *testing.T) {
diff --git a/src/pkg/exp/template/set.go b/src/pkg/exp/template/set.go
index 3aaabaad5a..bda4600192 100644
--- a/src/pkg/exp/template/set.go
+++ b/src/pkg/exp/template/set.go
@@ -56,7 +56,7 @@ func (s *Set) Parse(text string) (err os.Error) {
 	const context = "define clause"
 	for {
 		t := New("set") // name will be updated once we know it.
-		t.startParse(lex, tokens)
+		t.startParse(s, lex, tokens)
 		// Expect EOF or "{{ define name }}".
 		if t.atEOF() {
 			return
-- 
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